Extreme Lives, the final episode of Animals: The Inside Story, explores the limits of animal endurance. A polar bear uses its thick fur coat to turn light into heat and survive the Arctic cold. Hibernation is one way to endure winter but the rare Vancouver Island Marmot is on a knife-edge between life and death. Wood frogs enter a state of suspended animation, freezing 65% of their bodies to stay alive. The camel survives extremes of desert heat with amazing blood cells and a nose designed to conserve every drop of moisture.